Single crystal silicon is the starting material in many processes for fabricating semiconductor electronic components and solar materials. For example, semiconductor wafers produced from silicon ingots are commonly used in the production of integrated circuit chips. In the solar industry, single crystal silicon may be used instead of multicrystalline silicon due to the absence of grain boundaries and dislocations. Single crystal silicon ingots are machined into a desired shape, such as a silicon wafer, from which the semiconductor or solar wafers can be produced
Existing methods to produce high-purity single crystal silicon ingot include a float zone method and a magnetic field applied Czochralski (MCZ) process. The float zone method includes melting a narrow region of a rod of ultrapure polycrystalline silicon and slowly translating the molten region along the rod to produce a single crystal silicon ingot of high purity. The MCZ process produces single crystal silicon ingots by melting polycrystalline silicon in a crucible, dipping a seed crystal into the molten silicon, and withdrawing the seed crystal in a manner sufficient to achieve the diameter desired for the ingot. A horizontal and/or vertical magnetic field may be applied to the molten silicon to inhibit the incorporation of impurities, such as oxygen, into the growing single crystal silicon ingot. Although float zone silicon ingots typically contain relatively low concentrations of impurities, such as oxygen, the diameter of ingots grown using the float zone method are typically no larger than about 150 mm due to limitations imposed by surface tension. MCZ silicon ingots may be produced at higher ingot diameters compared to float zone ingots, but MCZ silicon ingots typically contain higher concentrations of impurities.
During the process of producing single crystal silicon ingots using the MCZ method, oxygen is introduced into silicon crystal ingots through a melt-solid or melt crystal interface. The oxygen may cause various defects in wafers produced from the ingots, reducing the yield of semiconductor devices fabricated using the ingots. For example, insulated-gate bipolar transistors (IGBTs), high quality radio-frequency (RF), high resistivity silicon on insulator (HR-SOI), and charge trap layer SOI (CTL-SOI) applications typically require a low oxygen concentration (Oi) in order to achieve high resistivity.
At least some known semiconductor devices are fabricated using float zone silicon materials to achieve a low Oi and high resistivity. However, float zone materials are relatively expensive and are limited to use in producing ingots having a diameter less than approximately 200 mm. Accordingly, float zone silicon materials are expensive and unable to produce higher diameter silicon crystal ingots with a relatively low oxygen concentration.
This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.